Detrend fMRI time series

Detrend fMRI dataset with a polynomial of given degree

fmri.detrend(data, degree = 1, nuisance=NULL, accoef = 0)

Arguments

data	fMRI dataset of class ''fmridata''
degree	Degree of the polynomial used to detrend the data. defaults to 1 (linear trends).
nuisance	Matrix of additional nuisance parameters to regree against.
accoef	Coefficient of AR(1) model used for prewhitening. default 0.

Details

The function can be used to detrend the time series of an fMRI dataset data (of class ''fmridata'' using polynomials. If the argument degree is larger than 0 (default: 1) the polynomial trends up to the given degree are removed from the data. If the argument accoef is larger than 0 (default: 0) prewhitening using an AR(1) model is performed.

Value

Detrended data object of class ''fmridata''.

References

Polzehl, J. and Tabelow, K. (2007). fmri: A Package for Analyzing fmri Data, R News, 7:13-17.

Author

Joerg Polzehl polzehl@wias-berlin.de

See also

fmri.lm

Examples

  # Example 1
  data <- list(ttt=writeBin(rnorm(32*32*32*107),raw(),4),
               mask=array(1,c(32,32,32)),dim=c(32,32,32,107))
  class(data) <- "fmridata"
  data <- fmri.detrend(data,2)
#> Start trend removal 
#> Finished trend removal